1. Field of the Invention
The present invention provides a simplified and inexpensive circuit for dimming light emitting diodes utilizing a conventional TRIAC AC dimmer.
2. Background of the Invention
Circuits for dimming incandescent bulbs have been available in the prior art. For example, U.S. Pat. No. 6,566,819 to Wolff discloses a light control/dimmer system that can be touch operated and includes a programmable timer that controls the light attached thereto by switching the device to an “OFF” position after a predetermined time period. In most dimmers, the current will not go to zero unless there is a minimum load provided by the device being dimmed. Thus, the dimmer device typically has a minimum load placed on it of approximately 5 watts.
Light emitting diodes (“LEDs”) that provide a specific, focused light output of a predetermined wavelength have been available for a number of years. U.S. Pat. No. 6,598,996 to Lodhie sets forth, inter alia, the advantages of using LEDs when compared to conventional incandescent bulbs. LEDs, in addition to replacing incandescent bulbs used in motor vehicles, have also been used for signage and other display systems. The illumination output from LEDs typically have a single intensity and are not easily adapted to having multiple levels of intensity and thus to dimming. Specifically, LEDs do not provide the minimum load necessary when used with conventional dimmers. Those LED circuits with dimmer devices draw higher power from the AC input source which, in turn, generates relatively higher heat levels which is undesirable in LED based circuits.
What is desired is to provide a circuit which enables LEDs to be dimmed and wherein the power/heat levels generated during LED use is substantially reduced.